EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 258 AM EDT FRI MAR 14 2014 VALID 12Z MON MAR 17 2014 - 12Z FRI MAR 21 2014 ...AN ACTIVE LATE WINTER PATTERN NEXT WEEK... ...GUIDANCE/UNCERTAINTY ASSESSMENTS... GIVEN THE AMPLITUDE OF ENERGETIC PACIFIC SYSTEMS IN WATER VAPOR LOOPS AND GUIDANCE...PREFER A MID-UPPER LEVEL MEDIUM RANGE PATTERN EVOLUTION DOWNSTREAM OVER THE LOWER 48 THAT HIGHLIGHTS THESE SYSTEMS ON THE AMPLIFIED AND LESS PROGRESSIVE SIDE OF THE FULL COMPOSITE ENVELOPE OF MODEL AND ENSEMBLE SOLUTIONS. HOWEVER...REMAIN HESITANT TO EMBRACE OUTLIER AMPLIFIED SOLUTIONS CONSIDERING RUN-RUN FLUCTUATIONS IN DETERMINISTIC MODELS AND ELEVATED FORECAST SPREAD/UNCERTAINTY. WITH THESE PATTERN PREFERENCES IN MIND...WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS ALONG WITH HPCGUIDE SENSIBLE WEATHER GRIDS WERE PRIMARILY DERIVED FROM A BLEND OF COMPATABLE/CLUSTERED GUIDANCE FROM THE 12 UTC ECMWF/ECMWF ENSEMBLE MEAN AND 18 UTC GFS ENSEMBLE MEAN DAYS 3/4 MON/TUE BEFORE SWITCHING TO MAINLY THE ECMWF ENSEMBLE MEAN DAYS 5-7 NEXT WED-FRI THAT MAINTAINS MAX PATTERN CONTINUITY. ...PATTERN OVERVIEW AND SENSIBLE WEATHER HIGHLIGHTS... MID-UPPER LEVEL FLOW INTO MON/TUE OFFERS LEAD NRN AND SRN STREAM TROUGHING OVER EAST-CENTRAL NOAM SHIFTING OFF THE EAST COAST. SRN STREAM BASED AND COMPLEX FRONTAL WAVES CONFIGUATION WILL ALLOW FOR AN AMPLE MOISTURE FEED FOCUS THROUGH THE SERN US WITH LOCALLY ENHANCED FRONTAL AND WARM SECTOR CONVECTION/RAINFALL OVER THE SERN US. UNSEASONABLY COLD HIGH PRESSURE FED OVERTOP ALSO ALLOWS THE THREAT OF LATE SEASON HEAVY SNOW AND ICE ON THE NRN PERIPHERY OF THE PCPN SHIELD FROM THE CENTRAL APPALACHIANS THROUGH N-CENTRAL MID-ATLANTIC INTO NEW ENGLAND WITH COASTAL POTENTIAL. THIS OCCURS AS AN UPSTREAM AND VIGOROUS NWRN US MID-UPPER LEVEL COOLING TROUGH AND LEAD FRONTAL PUSH DIGS LOCALLY AND TERRAIN ENHANCED PCPN SEWD THROUGH THE NWRN US THROUGH THE N-CENTRAL INTERMOUNTAIN WEST/ROCKIES/PLAINS MON/TUE...CONTINUING ONWARD OVER THE CENTRAL THEN ERN US WED-FRI AIDED BY ORGANIZED CYCLOGENESIS ALLOWING SNOW POTENTIAL ON THE NRN PORTION OF THE LOW TRACK/PCPN SWATH AND A WARMING PRE-FRONTAL AIRMASS. SCHICHTEL